Sauvegarde de la vidéo en cours de lecture en mpv --ytdl vers un fichier en cours de lecture

youtube-dl -o - | tee video.mp4 | mpv -

--record-file a été déprécié, au profit de --stream-record . Ces deux solutions ne sont pas parfaites, car une avance rapide au-delà du cache entraînera un saut dans le fichier de sortie.

de la page de manuel mpv :

--record-file=<file>
       Deprecated, use --stream-record, or the dump-cache command.

       Record the current stream to the given target file. The target file will always be overwritten without asking.

       This was deprecated because it isn't very nice to use. For one, seeking while this is enabled will be directly reflected in  the
       output, which was not useful and annoying.

 --stream-record=<file>
        Write  received/read  data from the demuxer to the given output file.
        The output file will always be overwritten without asking.
        The output format is determined by the extension of the output file.

        Switching streams or seeking during recording might result in recording
        being stopped and/or broken files. Use with care.

        Seeking outside of the demuxer cache will result in "skips" in the output file,
        but seeking within  the demuxer cache should not affect  recording. 
        One exception is when you seek back far enough to exceed the forward buffering size,
        in which case the cache stops actively reading.
        This will return in dropped data if it's a live stream.

        If this is set at runtime, the old file is closed, and the new file is opened.
        Note that this will write only data that  is  appended at the end of the cache,
        and the already cached data cannot be written.
        You can try the dump-cache command as an alternative.

        External files (--audio-file etc.) are ignored by this,
        it works on the "main" file only. Using this with  files  using  ordered
        chapters or EDL files will also not work correctly in general.

        There  are  some  glitches with this because it uses FFmpeg's libavformat for writing the output file.
        For example, it's typical that it will only work if the output format is the same as the input format.
        This is the case even if it works with  the  ffmpeg tool.
        One reason for this is that ffmpeg and its libraries contain certain hacks and workarounds for these issues,
        that are unavailable to outside users.

        This replaces --record-file.
        It is similar to the ancient/removed --stream-capture/-capture options,
        and provides better  behavior in most cases (i.e. actually works).

l'usage : mpv --stream-record=$HOME/Downloads/path/name.mp4 <URL>

Youtube-dl url --exec mpv

Il ne s'agit pas de streaming mais de lecture après téléchargement, mais vous ne verrez pas la différence à moins d'avoir un compte dialup ou autre.